Prior art describes a numerous types of devices for control of overflow levels in bath tubs and for alarming a user of bathtub overflowing. There are also a lot of devices intended to monitor the bathtub water temperature at the user's desire.
One of such devices is disclosed in a U.S. Pat. No. 6,956,486 to Robert L. King, Jr., as follows: “A bathtub water level monitoring system for alerting a user upon acquisition of a pre-selected level in a bathtub. The bathtub water level monitoring system includes a bathtub, a main unit adapted for attachment to an interior face of a bathtub, the main unit having a plurality of water sensors aligned along a lower portion of the main unit. The main unit further includes a transmitter and alarm system for producing an audible alarm upon the water sensor detecting a predetermined water level. The system includes a remote alarm device for giving an audible alarm upon reception of a signal transmitted from the transmitter of the main unit.” The device of that patent is substantially installed inside the tub, which is often inconvenient to users. It does not provide for a means to shut off the incoming water flow, in case the user does not hear the alarm sound, e.g. when she left the house and forgot about the bath.
Another device is exemplified in a U.S. Pat. No. 7,096,522 to R. Eric Hirtriter, that comprises an alarm “adaptable to common American bathtub cover plate configurations.” That invention chiefly deals with attachment arrangements of the device, which device is also substantially installed inside the tub. It does not provide for a means to shut off the incoming water flow, in case the user is not at home and forgets about the bath.
A U.S. Pat. No. 7,068,175 to Larry Pennington teaches: “A water level warning device for use in conjunction with a bathtub or a sink for audibly warning a user when the water flowing into the bathtub or sink has reached a predetermined level. The warning device comprises a cylindrical tube containing a floating ball and having a plurality of circular openings extending fully therethrough for allowing water from the bathtub or sink to enter the tube. The top of the tube has a pressure activated sensor and a speaker in communication with the sensor. The height of the tube may be telescopically adjusted by the user . . . the floating ball floats upon the upper surface of the water entering the tube, and activates the sensor when the level of water reaches the top of the tube. Upon selective activation of the sensor, the speaker emits an audible alarm.” In detail, it explains: “The circular bottom 12B of the tube 12 has a suction cup 18 attached thereunto, for firmly anchoring the warning device 10 to the base of the bathtub.” Similarly to those described in the aforementioned patents, that device is intended for installation inside the tub to be attached to its bottom. It does not provide for a means to shut off the incoming water flow, when the user does not hear the warning sound of the speaker.
Another U.S. Pat. No. 6,732,388 to McKenna, entirely incorporated hereby by reference, describes “An overflow system suitable for use in controlling the level of water in, for example, a bathtub (3) is described. The overflow system comprises a conduit attached to the overflow outlet (21) of the bathtub (3) and is arranged so that when the bathtub (3) is overfilled, any excessive flow rate of overflow water through the conduit (19) is detected. The excessive flow rate is detected by arranging for the outlet (25) of the conduit to have a smaller maximum flow rate than the inlet (23) of the conduit so that water backs up within the conduit during an excessive flow rate condition. The backed up water may be detected by a reed switch (31) in conjunction with a magnetic float (27) in order to actuate a solenoid valve (9) to prevent any more water from entering the bathtub (3).” That invention contemplates substantial alterations to the existing plumbing arrangements for known bathtubs, and thus would entail significant additional expenses.
A published U.S. patent application 2005/0251906, entirely incorporated hereby by reference, teaches “A control system for filling a bathtub which automatically shuts off the bathtub faucet when the water has reached a desired level, by detecting a volume of water that has passed through the dispensing pipe or a level of water in the bathtub. In the preferred embodiment a timer is provided to automatically shut off the bathtub faucet after a preset time interval, as a backup or as an independent filling regulator. In one embodiment a temperature sensor or timer is provided to adjust the flow of hot water and cold water as necessary to maintain a constant temperature which has been set by the user. In another embodiment one or more timers are provided to control the flow of hot water and cold water separately as necessary to reach the desired temperature.” The system, described in that patent application, is capable to additionally regulate the water temperature in the bathtub. That construction though requires certain alterations of the existing bath plumbing arrangements.
Liquid level switches, also known as reed-style switches, are mounted to the inside of a tank and are activated when the liquid content reaches the float. As the float rises and falls, a magnet attracts and releases the contacts, opening and closing the switch. Therefore, such a switch would need to be mounted to the interior of the bathtub that is not always acceptable to the users.